Preparation of Biodegradable Polymer Copolyesteramides from L-Lactic Acid Oligomers and Polyamide Monomers

Biodegradable copolyesteramide was synthesized from L-lactic acid oligomers and polyamide monomers to improve the properties of poly(lactic acid). The oligomer was synthesized from L-lactic acid using direct polycondensation process at 170 oC, 30 torr for 7h. p-Toluenesulfonic acid used as a catalyst. From 1H NMR analysis the oligomers have degree of polymerization of ca. 5. The L-lactic acid oligomer (OLLA) was subjected to reacted with ɛ-caprolactam (CLM) with different ratios: 90:10, 80:20, 70:30 and 60:40 using SnCl2·2H2O as a catalyst at 130, 150 and 170 oC pressure 30 torr for 3h. The synthesized polymers were subjected to thermal property analysis using DSC technique and analyzed the functional groups with FT-IR. It was found that the melting temperature of the polymers increased with increasing amounts of CLM but decreased when the amount of CLM exceeded 30 percent. FT-IR analysis confirmed structure of copolyesteramide comprised of amide ide units and lactate unit.